The invention relates to a data carrier comprising an electric circuit, which circuit has a circuit terminal for supplying a carrier signal and includes supply voltage generation means for generating a DC supply voltage while the carrier signal is used, and which has a supply circuit point from which the DC supply voltage can be tapped, and which includes control means for controlling the DC supply voltage in accordance with a controlled variable signal that occurs at a control means circuit point and represents the carrier signal.
The invention further relates to a circuit for a data carrier, which circuit has a circuit terminal for supplying a carrier signal and includes supply voltage generation means for generating a DC supply voltage while the carrier signal is used, and which has a supply circuit point from which the DC supply voltage can be tapped, and which includes control means for controlling the DC supply voltage in accordance with a controlled variable signal that occurs at a control means circuit point and represents the carrier signal.
Such a data carrier of the type defined in the opening paragraph, having a circuit of the type defined in the second paragraph has been marketed by the applicants and is therefore known.
With the known data carrier, a carrier signal, that is received by transmission means and is delivered by transmitter means of a communication arrangement is applied to the circuit via the circuit terminal of the data carrier circuit and is rectified by rectifier means and the rectified signal is applied to a storage capacitor. The rectifier means and the capacitor form supply voltage generation means which are arranged for generating a DC supply voltage and have the supply circuit point from which the DC supply voltage can be tapped that is used for supplying power to first useful circuit components connected to the supply circuit point. Furthermore, the control means are connected to this supply circuit point. The control means recover from the DC supply voltage a controlled variable signal that appears on the control means circuit point and represents the carrier signal via the DC supply voltage derived by the carrier signal. The control means are arranged for controlling the DC supply voltage in accordance with the controlled variable signal, while the rectifier means are loaded in dependence on the controlled variable signal when the control is performed by a field effect transistor. Also the carrier signal is indirectly loaded or controlled, respectively, via the loading of the rectifier means. The known data carrier, however, also includes second useful circuit components which are to be connected directly to the circuit terminal, as is the case, for example, with a load modulation means which is provided for modulating the load of the carrier signal.
The known data carrier has a problem that the control means have a control dynamic that is disadvantageously slowed down due to the storage capacitor connected to the supply circuit point, so that a rapid control of the DC supply voltage or a rapid indirect control of the carrier signal respectively, is not guaranteed when the intensity of the carrier signal varies rapidly, as this would be necessary, for example, for an application in which the data carrier is present in the vicinity of the transmitter means of a communication station that was not transmitting at that moment and during its presence is activated to transmit the carrier signal. In that case, due to the slowed-down control dynamic of the supply voltage control on the circuit terminal there are significantly higher voltage values than the value of the DC supply voltage appearing on the supply voltage circuit point. In consequence, this means that the second useful circuit components, compared to the supply voltage generation means and the first useful circuit components are to have a higher voltage stability. When an integrated circuit is manufactured, however, this fact is the cause of a considerable technical disadvantage, because a second manufacturing process is to be used for the second useful circuit components, which second process differs from a first manufacturing process of the supply voltage generation means and the first useful circuit components, so that the manufacture of the data carrier is made considerably more expensive.
It is an object of the invention to resolve the problems defined above with a data carrier in accordance with the type defined in the opening paragraph and with a circuit in accordance with the type defined in the second paragraph and provide an improved data carrier and an improved circuit.
The object defined above is achieved with a data carrier of the type defined in the opening paragraph in that decoupling means are provided with the aid of which the supply circuit point and the control means circuit point can be decoupled from each other.
The object defined above is furthermore achieved with a circuit of the type defined in the second paragraph in that decoupling means are provided with the aid of which the supply circuit point and the control means circuit point are decoupled from each other.
Providing the characteristic features according to the invention advantageously achieves that with the aid of the control means, unaffected by the supply voltage generation means and unaffected by the first useful circuit components, the carrier signal that occurs on the circuit terminal and thus also the supply voltage that can be tapped from the supply circuit point can be controlled. Furthermore, the advantage is obtained that on the circuit terminal no significantly higher voltage values occur than the voltage value of the DC supply voltage occurring on the supply voltage circuit point. This further offers the advantage that the second useful circuit components may have a voltage stability that is identical with the first useful circuit components and, therefore, a single manufacturing process can be used for manufacturing the circuit.
Providing the characteristic features according to the invention and as defined in claim 2 or claim 10, respectively, advantageously makes a reliable decoupling possible of the supply circuit point from the control means circuit point. Furthermore, the advantage is obtained that the diode configuration is also used as a rectifier for supplying power to the capacitor of the supply voltage generation means and that the diode configuration only needs to be dimensioned for power values that are low compared to the control means. This allows a highly surface-area saving realization of the decoupling means when an integrated circuit is manufactured.
Providing the characteristic features according to the invention and as defined in claim 3 or claim 11, respectively, advantageously makes it possible that separately structured load modulation means for modulating the load of the carrier signal can be omitted, because only the control means are used for modulating the load and that, as a result, surface area is definitely saved when an integrated circuit is manufactured, because the load modulation means dimensioned for high-current values are formed completely with the parts of the control means already dimensioned for high-currents. Furthermore, the advantage is obtained that a saturation behavior typical of the control means can be used for limiting an intensity of the load modulation of the carrier signal. This furthermore offers the advantage that with the data carrier a load modulation of the carrier signal can be generated, whose intensity is variable in dependence on an intensity of the received carrier signal. As a result, the advantage is furthermore obtained that receiving means of a communication arrangement can be prevented from being overmodulated, which receiving means receive the load-modulated carrier signal with the aid of the data carrier.
Providing the characteristic features according to the invention and as defined in claim 4 or claim 12, respectively, advantageously achieves that for the purpose of modulating the load of the carrier signal with the aid of the load modulation means formed by parts of the control means, a modulation signal received by the control means is used for controlling the value of the controlled variable signal, so that the controlled variable signal, which the control means use for controlling, represents the modulation signal which the load modulation means use for modulating the load.
Providing the characteristic features according to the invention and as defined in claim 5 or claim 13, respectively, advantageously achieves that a first value of the controlled variable signal and a second value of the controlled variable signal can be generated reliably and reproducibly.
Providing the characteristic features as defined in claim 6 or claim 14, respectively, advantageously achieves that the controlled variable signal can be generated in a simple and disturbance-free manner.
In a data carrier according to the invention and a circuit for the data carrier according to the invention, the tapping means can be formed, for example, by an electronic reversing switch. However, it has proved to be advantageous to provide the characteristic features as claimed in claim 7 or claim 15, respectively, because in this way a full integration of the circuit is possible. Furthermore, the advantage is obtained that it is possible in a very simple manner to drive the tapping means with the modulation signal preferably available in digital form.
With a data carrier according to the invention and a circuit according to the invention, providing the characteristic features according to the invention and as defined in claim 8 or claim 16, respectively, has proved to be advantageous because, as a result, a highly cost-effective manufacture in an associated large number is guaranteed.
The aspects defined above and further aspects of the invention become evident from the examples of embodiment to be described hereinafter and will be explained with reference to these examples of embodiment.
These and other aspects of the invention are apparent from and will be elucidated with reference to the embodiment(s) described hereinafter.